Proportional frame twist slope control

ABSTRACT

A system is disclosed for controlling the slope of an earth working machine which is propelled by at least four support means, for example tracks or wheels, wherein the slope of the distortable machine frame is adjusted with respect to these support means and wherein the control system particularly comprises a slope sensing means for controlling the slope across the rear end of the frame of the vehicle and a torsion sensing means for controlling the slope across the front end of the frame of the vehicle.

United States Patent [1 1 Knntz .111] 3,857,577 1 Dec. 31, 1974 PROPORTIONAL FRAME TWIST SLOPE 3,214,185 12/1965 Mason 28()/6.l CONTROL 3,237,958 3/1966 Saftien Z80/6.l [75] Inventor: Leland Kuntz, Arlington Heights, Primary Examiner philip Goodman Attorney, Agent, or Firm-Trevor B. Joike [73] Assignee: Honeywell Inc., Minneapolis, Minn. 22 Filed: Sept. 28, 1973 [57] ABSTRACT A system is disclosed for controlling the slope of an [21] Appl' 401,927 earth working machine which is propelled by-at least four support means, for example tracks or wheels, [52] US. Cl. 280/6.1', 280/124 B wherein the Slope of the dlstortable machine frame is [51 Int. Cl. B60g 17/04 adjusted with respect to these support means and [58] Field of Search 280/124 12 124 B, 6.6 H, wherein the control System particularly comprises a 12 1 11 0 5 slope sensing means for controlling theslope across the rear end of the frame of the vehicle and a torsion 5 References Cited sensing means for controlling the slope across the UNITED STATES PATENTS front end of the frame of the vehicle. 3,028,175 4/1962 Eckman 280/6.l 8 Claims, 3 Drawing Figures i 29 as G K 56 34 1 G 32 \l/ L 27 37 A, '4 15 V J33 PATENTED D533 1 7 sum 10F 2 PATENTEDum 1 I974 3,857, 577

sum 20F 2 2e 25 R A SENSOR AMP. A E M FIG 3 I? l3 l4 l8 PROPORTIONAL FRAME TWIST SLOPE CONTROL BACKGROUND or THE INVENTION In earth working machines, such as graders and pavers, where the slope and grade are controlled by controlling the transverse slope and the elevation of the both slope sensors such that one of the slope sensors will track the other slope sensor, i.e.,.to operate both the front end of.the frame and the rear end of the frame at substantially identical slope angles or at a substantially precise offset. v

To overcome this difficulty, the prior art provided a slope sensor at the rear end of the machine for controlling the slope across the rear end of the machine and provided a torsion bar for sensing the frame distortion. The frame distortion was used to control the slope angle across the front end of the machine However, this frame distortion sensor was operated in an on-off manner which, therefore, had all of the detriments of such systems. In this on-off system, the longer part of an L shaped bar was extended across the machine; thus, as the machine frame was distorted, the shorter part rotated. A pair of limit switches were positioned to sense movement of the shorter part, one switch was actuated as the part rotated up and the other switch was actuated as the part rotated down. The switches controlled the slope across the front end of the frame. Onoff systems were, however, incapable of providing both high positioning speeds and a narrow dead band (dead band here is definedas the distance between the two limit switches). If the On-Off system were operated at high speeds and narrow dead bands, the system would overshoot causing cyclical operation of the control system and result in a wavy roadway. Thus, it was necessary to operate on-off systems either at low speeds and narrow dead bands which, because of the slow speeds, resulted in inadequate compensation for error signals or at high positioning speeds and wide dead band which allowed for too much error.

SUMMARY OF THE INVENTION The disclosed invention overcomes these detriments by providing proportional control of both the slope of the rear end of the machine and the slope of the front end of the machine. The proportional system eliminates these detriments and difficulties by providing means is utilized in conjunction with the rotation of this torsion bar to provide a proportional signal to control the slope across the front end of the machine frame.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a simplistic top view of a machine frame with a typical control system mounted thereon.

FIG. 2 shows a side view of such a machine without the control system.

FIG. 3 shows a schematic diagram of the control systerm used in this invention.

DETAILED INVENTION FIG. 1 shows a machine designated generally by reference numeral 10 having a machine frame 11 supported on support means, shown here as wheels 12, by arms 13-16. Hydraulic cylinders 1720 connect the support means 12 to their respective arms 13-16.

Thus, each corner of the machine frame 11 can be independently raised and lowered. and the slope can be controlled by properly operating the hydraulic rams 17-20.

The slope sensor 21, which may be in the form of a gravity operated pendulum, is mounted on the rear of the machine frame 11 and senses the slope angle across the rear end of the frame. The output from the slope sensor is fed to a servo valve 22 which controls the hydraulic ram 18.

FIG. 3 shows an example of a control system which may be used for the control systems shown in FIG. I.

- The slope sensor 21 may take the form of thetype 134,847A sensor manufactured by the assignee of this application and it providesan output to an amplifier which may be type R7232A also manufactured by the assignee. A second input to the amplifier is derived from a potentiometer 23 which is utilized as a setpoint. The amplifier 26 provides an output which is proportional to the deviation between the actual slope sensed by the sensor and the reference as established by the potentiometer 23. This proportional output is-used to control a servo valve 25 which may take the form of a type V7,'059A valve also manufactured by the assignee. The output from the servo valve is proportional to the input of the valve and is used to control the hydraulic ram. The hydraulic ram adjusts its corner of the machine by an amount which is proportional to its input. In FIG. 1, a torsion bar 27 is also provided to measure the distortion of the frame which may occur whenever the slope across the front of the frame deviates from the slope across the rear of the frame. The torsion bar or torque tube 27 is fixed to the right side of the frame and supported at the left side by a bar 28 and bearing 29. A sensor 30, which may take the form a type SBl04A manufactured by the assignee of this application, is used to sensethe mogement or rotation flexing of the torsion bar.27. The sensor 30, mounted to the left side of the machine by support 40, provides an output which is proportional to frame distortion and is used to control a valve 31 which provides'an output to the hydraulic ram 17. The control circuit which includes the'sensor 30 and the valve 31 may again take the form of FIG. 3. The torsion bar 27 can also be mounted from front to back. in which case the sensor 30 must be supported at the end where the torsion bar' is supported by the bearing.

Means are also provided to control the elevation of the machine. In this case, a string line or wire 33 is ex 3 tended alongside the machine and two grade sensors 34 and 35 mounted on the machine frame by bars 36 and 37 respectively sense the deviation of the machine frame from the reference established by the wire 33. EAch of the grade sensors provides an output, proportional to this deviation, to respective servo valves 38 and 39 which in turn provide respective proportional outputs to the hydraulic rams 20 and 19. These control systems may again take the form of the system shown in-FIG. 3. If the machine frame deviates from the reference established by wire 33, the deviation is sensed by the grade sensors 34 and 35 which provide outputs to the hydraulic rams 20 and 19 to adjust the elevation of the machine frame 11 to bring it in proper alignment with the wire 33. The slope sensor 21 and torsion bar 27 then sense any deviation of theslope of the frame to provide the proper corrective action.

Should the front end of the machine frame 11 fail to maintain the proper slope, the deviation will be sensed by the torsion bar 27 and the control system comprising elements 30-32 will provide the proper corrective sigrials to the hydraulic ram 17. If the rear end of the machine should deviate from the predetermined slope, the control system comprising elements 21-22 will provide proper corrective signals to the hydraulic ram 18.

It is apparent that the disclosed system may be modified in certain respects. For example, the servo valves may be replaced by servo motors while at the same time the hydraulic rams may be replaced by jack screws. As another example, the slope sensor 21 may 7 be placed on the front of the machine to control ram 17 and the servo valve 31 may be connected to control ram 18.

The embodiments of the invention in which an exclusive property or right is claimed are defined as follows: 1. A control system for an earth working machine having earth-support means and a frame having'a front end and a rear end and power means for adjusting the.

grade and slope of the frame relative to said support means, said system comprising:

slope sensing means for providing an output dependent upon the deviation of the actual slope across one of said ends from a predetermined setpoint; first connecting means adapted to connect said output to saidrpower means for controlling the slope of said one end; frame twist sensing means for providing a twist output proportional to the deviation of the actual slope across the other of said ends of said frame from the actual slope across said one end;

control means for receiving said twist output and for providing a control output proportional to the deviation of said twist output from a predetermined setpoint; and,

second connecting means adapted to connect said control output to said power means for controlling the slope across said other end of said frame.

2. The system of claim 1 wherein said frame twist sensing means comprises a torsion bar.

3. The system of claim 2 wherein said control means comprises a sensor for providing a signal proportional to the movement distortion of said torsion bar.

4. The system of claim 1 further comprising grade sensing means responsive to a preset reference for controlling the elevation of the frame with respect to' the support means.

5. The control system of claim 4 wherein said frame twist sensing means comprises a torsion bar.

-6. The system of claim 5 wherein said control means comprises a sensor for providing a signal proportional to the movement distortion of said torsion bar.

7. The system of claim 1 wherein said frame twist sensing means comprises a torsion bar extending across said machine, and said control means comprises a sensor for providing a signal proportional to the movement of said torsion bar resulting from the deviation of said actual slope of said other end from the actual slope across said one end, amplifier means connected to said sensor for receiving said proportional signal and for providing an amplified proportional signal and servo valve means for receiving said amplified proportional signal and adapted to proportionally control said power means. v

8. The system of claim 7 wherein said slope sensing means comprises a slope sensor for providing a signal proportional to the slope across the rear end of said frame, an amplifier connected to said sensor for receiving said proportional signal and for providing an amplified proportional signal and a servo valve means adapted to receive said amplified proportional signal and for proportionally controlling the slope of the rear end of said frame with respect to the support means. 

1. A control system for an earth working machine having earthsupport means and a frame having a front end and a rear end and power means for adjusting the grade and slope of the frame relative to said support means, said system comprising: slope sensing means for providing an output dependent upon the deviation of the actual slope across one of said ends from a predetermined setpoint; first connecting means adapted to connect said output to said power means for controlling the slope of said one end; frame twist sensing means for providing a twist output proportional to the deviation of the actual slope across the other of said ends of said frame from the actual slope across said one end; control means for receiving said twist output and for providing a control output proportional to the deviation of said twist output from a predetermined setpoint; and, second connecting means adapted to connect said control output to said power means for controlling the slope across said other end of said frame.
 2. The system of claim 1 wherein said frame twist sensing means comprises a torsion bar.
 3. The system of claim 2 wherein said control means comprises a sensor for providing a signal proportional to the movement distortion of said torsion bar.
 4. The system of claim 1 further comprising grade sensing means responsive to a preset reference for controlling the elevation of the frame with respect to the support means.
 5. The control system of claim 4 wherein said frame twist sensing means comprises a torsion bar.
 6. The system of claim 5 wherein said control means comprises a sensor for providing a signal proportional to the movement distortion of said torsion bar.
 7. The system of claim 1 wherein said frame twist sensing means comprises a torsion bar extending across said machine, and said control means comprises a sensor for providing a signal proportional to the movement of said torsion bar resulting from the deviation of said actual slope of said other end from the actual slope across said one end, amplifier means connected to said sensor for receiving said proportional signal and for providing an amplified proportional signal and servo valve means for receiving said amplified proportional signal and adapted to proportionally control said power means.
 8. The system of claim 7 wherein said slope sensing means comprises a slope sensor for providing a signal proportional to the slope across the rear end of said frame, an amplifier connected to said sensor for receiving said proportional signal and for providing an amplified proportional signal and a servo valve means adaptEd to receive said amplified proportional signal and for proportionally controlling the slope of the rear end of said frame with respect to the support means. 